Embryology of the GI tract

Question 1

What does the endoderm layer give rise to in the GU tract?

Answer 1

Epithelium of mucosa (epithelial lining)

Associated ducts and glands

Question 2

What does the visceral mesoderm layer give rise to?

Answer 2

Lamina propria
Muscularis mucosa and Muscularis externa
CT of submucosa and External CT

Question 3

What do the ventral mesenteries give rise to?

Answer 3

Lesser omentum

Falciform ligament

Question 4

What do the dorsal mesenteries give rise to?

Answer 4

Dorsal mesogastrium
Dorsal mesoduodenum
Dorsal mesocolon

Question 5

What does rotation of different parts of the gut bring about?

Answer 5

Brings the mesenteries into their final positions

Question 6

Describe the development of the oesophagus? Week 4,5 and 8?

Answer 6

Week 4 - distinguishable
Week 5 - circular muscle develops
Week 8 - longitudinal muscle develops

Question 7

How does the stomach develop?

Answer 7

The stomach develops as a dilatation in the foregut that rapidly enlarges asymmetrically, giving rise to the greater curvature of the stomach.

Question 8

What does growth and rotation of the stomach creat?

Answer 8

Growth and rotation of stomach creates the lesser sac and causes the dorsal mesentery to bulge

Continued growth of the dorsal mesentery forms the greater omentum

Question 9

How do the lesser omentum and the falciform ligament form?

Answer 9

Lesser omentum and falciform ligament form from the ventral mesentery

Question 10

Describe how the duodenum is made?

Answer 10

The caudal portion of the foregut makes up the 1st and 2nd part of the duodenum

The cranial portion of the midgut forms the 3rd and 4th part of the duodenum

Question 11

What happens to the duodenal loop as the stomach rotates?

Answer 11

the duodenal loop is directed to the right due to the rotation of the stomach

Question 12

What does the liver bud grow into?

Answer 12

The mesoderm of the septum transversum

Question 13

What does the endoderm form in relation to the liver and gall bladder?

Answer 13

Liver cells

Lining of the biliary tree

Question 14

What does the ectoderm give rise to in the GI tract?

Answer 14

Lining of the closely related resp tract and some of the epithelial of the mouth and anus

Question 15

What does the septum transversum give rise to in relation to the liver and gall bladder?

Answer 15

Hematopioetic cells
Kupffer cells
Connective tissue

Question 16

What happens if the rotation of the pancreatic bud is incomplete?

Answer 16

If rotation of the pancreatic buds is incomplete, a ring of pancreatic tissue may surround the duodenum – called the annular pancreas.

Question 17

What is the spleen derived from?

Answer 17

The mesoderm - NOT THE GUT TUBE

Question 18

What is part of the midgut?

Answer 18

Second part of duodenum
Jejunum
Ileum
Caecum and appendix
Ascending colon
Proximal 2/3 of transverse colon

Question 19

Describe the re-entry of the midgut to the body cavity?

Answer 19

Occurs in week 10

Small intestine return first Caecum is last to reenter

Question 20

What is a common congenital defect of the small intestine?

Answer 20

Merkel’s diverticulum - a small diverticulum in the intestine